In a small bowl, combine butter, lime zest, chili powder, garlic, salt, and pepper. Set aside.
Without detaching the cornhusk from the ear, carefully pull it back and remove the silk from the corn. Replace the husks, and soak the corn in water at least 30 minutes. If the husks are too loose, secure them with kitchen string.
Remove the ears from the water and drain. Peel back the husks and dry the ears with a clean towel.
Spread the butter mixture evenly onto corn. Replace the husks and grill for about 25 minutes, or until tender, turning about every five minutes.